SELECT SUM(Stddev/AvP * cnt)/SUM(cnt) FROM ( SELECT Brand, Family, Series, MAX(Price) AS MaxP, AVG( Price ) AS AvP, MIN(Price) AS MinP, STDDEV(Price) AS Stddev, Count(ItemID) AS cnt FROM training_data WHERE LENGTH(Series) > 0 AND Series != "XP" GROUP BY Brand, Family, Series, CPUType, CPUCores, CPUSpeed, RAM, HDD, LCD, OS, Drive, ItemCondition HAVING (Count(ItemID) > 1)) AS Equivalences Result: 0.088 Which means the following: A difference in eBay laptop prices for exactly the same laptops is 8... read more
